Hydraulic rotary well drilling machines

ABSTRACT

The object of the invention is to furnish a new and improved form of Hydraulic Rotary Well Drilling Machine actuated by a positivedisplacement torque-producing sub-unit or units adapted to thrust-resisting sub-units above and below comprising the assembly of a power-driven rotary tool holder usually known by the general term of &#34;Turbo-drill.&#34;

United States Patent Warder 1 Apr. 8, 1975 [541 $122335? ROTARY WELLDRILUNG FOREIGN PATENTS OR APPLICATIONS 803.7[5 Ill/I958 United KingdomMil/2H) [76] Inventor: George E. Warder, l9 Vaughan Ave. Stamford Brook.London. E l d Primary E1\'un1inerC. J. Husar Ass/stun! E.\uminerO. T.Sessions F'led: Artur/10y. Age/1L 0r Firm-Hall & Houghton [2]] Appl,No.: 388,272

{} Foreign Application Priority Data [57] ABSTRACT Aug. [7, l972 UnitedKingdom 38339/72 The object of the invention is to furnish a new and im-52 11.5. c1. 418/211; 175/107; 418/217; Provcd form of Hydraulic RotaryDrilling 41g 23 chine actuated by a positive-displacement torque- [5 l]Int. Cl. .i F031: 3/00 Producing mils adapted to thrust-resisting 5 i fSearch 4 3 33 330 323 239 sub-units above and below comprising theassembly of g/333 233 317 319 311 3 3 34 a power-driven rotary toolholder usually known by 413/213; 7 m the general term ofTurbo-drilli[56] References Cited 7 Claims. 5 Drawing Figures UNITED STATES PATENTS1.2931459 2/l9l9 Johnson 4lH/2Il PATENTEDAPR 81975 HYDRAULIC ROTARY WELLDRILLING MACHINES The invention consists of certain parts and detailsand combinations of same. based on one type of machine constructedaccording to the invention cited. adapted to the practice of rotary welldrilling or to other cognate uses. that is to say to tunnel boring.sewer clearing or the like remote rotary tool operating.

In the accompanying drawings:

FIG. I is a isometric perspective view. partially cut away and partiallydisplaced. of a torque producing hydraulic motor subassembly accordingto the invention;

FIG. 2 is a horizontal section taken on the plane X-x of FIG. I viewedin the direction of the arrows FIG. 3 is a horizontal section similar toFIG. 2, with the rotor and stator displaced 45 from the position of FIG.2, and showing a modified construction;

FIG. 4 is a vertical section of a thrust bearing subassembly formed toreceive and cooperate with one or more of the motor sub-assembliesaccording to FIG. I;

FIG. 5 is a similar view showing a rotary tool holder and thrust bearingsub-assembly adapted for assemblage to the lower end of a torqueproducing subassembly according to FIG. I.

REFERRING TO THE DRAWINGS IN MORE DETAIL FIG. I is an illustrativesectional view of one hydraulic positive-displacement torque-producingsub'unit. showing a portion of one stator segment 1 broken away toreveal annular recesses or chambers 3. 3 and a slideway 8 for a vane.

The torque-producing sub-unit includes a stator l conforming externallyto the bore 2 of a drill stem pipe. said stator comprising four segmentsfor case of manufacture and assembly.

The stator I has a cylindrical bore, with two internal annular recessesor chambers 3,3 spaced axially and includes four axial radial slots 8within the bore spaced angularly at 90 degrees in planes including theaxis, formed half in each adjacent segment, somewhat deeper than theannular recesses 3,3 forming guideways for vanes.

A rotor 4 has a cylindrical external surface fitting within the statorI, and includes two pairs of abutments 5, each pair arrangeddiametrically opposite and in axial alignment in positions to fitclosely into and occupy portions of the annular recesses 3,3 formed inthe stator l, dividing each of them into two chambers.

Inlet ports 6 and outlet ports 7 are included in the rotor 4,respectively admitting supply fluid at pressure P/S and passing outgoingfluid at pressure P/O located adjacent to the radial faces of theabutments 5 and so elongated arcuately that during rotation when theyare crossing the vanes the hydraulic pressures on the opposite faces ofthe vanes are equalized, reducing the work of moving them axially.

Four vanes, 9,10,, 12 essentially not fewer than two for each abutment,are shown. vanes 9,10 being in their axially displaced position so thatthe abutments 5,5 projecting from the rotor 4 are passing thru theirgateways 18,18 while vanes 11 (slightly canted for visibility) and 12(not shown; se FIG. 2) are in their active positions crossing anddividing two half-chambers 3,3 simultaneously, and receiving thereaction of the hydraulic force P/S acting on the adjacent abutmentsprodueing torque. Each pair of abutments exerts a couple about the axis.

Said vanes touch the rotor 4 along one of their edges which match itsradius, whilst partially occupying and sliding in the slots 8 in thestator l.

Passages I3,I4,I5,l6 passing axially thru the rotor 4 communicate withrespective inlet and outlet ports 6.7. the passages 13, and 14 (notshown in this FIG. see FIG. 2) containing fluid at supply pressure P15.and passages I5.I6 conveying fluid at the outlet pressure W0.

A central passage I7 is included in the rotor 4 passing fluid at thesupply pressure P/S. leading via a thrustbearing sub-unit (FIG. 5]assmebled below the torqueproducing sub-unit FIG. 1 to a spring-loaded"dumping valve" 33.

The vanes 9.I0,Il,l2 are moved axially in pairs by means of a cam 19included in the rotor 4, so that a pair of gateways [8,18 in each vanecoincides with and allows the passage thru them of the abutments 5.5 atone extremity of the travel of the vanes, and they cross and divide thechambers 3.3 at the other extremity of travel.

When the vanes are in the latter, or active. position. their gateways18.18, full of fluid, are clear of the chambers which they cross and thevanes are subject to the difference of hydraulic pressure on theiropposite faces whilst not in motion.

The cam I9 controlling and displacing the vanes takes the form ofagroove in the rotor 4 engaging camfollowing projections 36 on the vanes,and having sinusoidal axial ramps and dwell arcuate portions. so thatthe vanes are displaced with the minimum of work during their simpleharmonic motion and are held stationary while said abutments pass thrusaid gateways and while the vanes are subjected to difference of fluidpressure on their opposite faces in turn.

Means for fixing the abutments 5 to the rotor 4 are furnished by dowels20, each provided with a tapped hole for its extraction, allowing anuninterrupted cylindrical surface on the rotor 4 to be produced, butother metallurgical methods of manufacture may allow the abutments to beformed integrally with the rotor as illustrated in FIG. 3. Mouldingmethods of manufacture may be applied to all components, since theclosest of fits are not essential the whole may be constructed virtuallywithout machining. All leakage fluid flows usefully thru the toolattached below the lower thrust beaing sub-unit (FIG. 5), and in view ofthe more than adequate pumping energy usually employed considerablelosses due to wear can be accepted. So long as the necessary pressuredifference across the inlet and outlet of the hydraulic machine can bemaintained, the necessary torque will be produced.

The rotor 4 is furnished at both ends with dog couplings 21 to mate withthose of adjacent sub-units above and below, and the passages 13,14,17each containing fluid at the supply pressure P/S. are coupled tocorresponding passages in the adjacent sub-units by connecting sleeves28.

In the couplings between the rotor 4 and the thrust bearing sub-unitabove (FIG. 4) which is blind as regards outlet fluid passages, andbetween the rotor 4 and thr rotating tool holder and thrust sub-unitbelow, (FIG. 5) the outlet passages are not coupled by connectingsleeves as 28, so that balanced end-thrust due to the outlet pressureP/O acts on the cross-sectional areas of both ends of the rotor 4 andthe only endthrust thereon, borne by the abutments 5,5 rotating in theannular recesses 3.3 in the stator l is due to the weight of the rotor.The leakage from each end of the rotor mixes with the outlet fluid.

Assembly oi the subunits described into a drill stem may be facilitatedby the use of slave guide rods inserted into the passages 13.14.17. uponwhich the con necting tubes 28 are slipped, in order to engage the dogCouplings 21 whilst each outer pipe is screwed onto the next above.

FIG. 2 illustrates a cross section on X-X (FIG. 1) showing an angularposition at which two vanes 9.10 are fully displaced axially and theabutments 5,5 are passing thru the gateways 18.18.clearance. fulloffluid, being prmided on both sides of the abutments which areessentially thicker than the \anes. to reduce the requirements ofprecision in the cam mechanism. and also at the Iintels" of thegateways.

Two vanes 11,12 are shown dividing the halfchambers 3,3 providingreaction to the fluid pressure propelling the abutments 5.5. Means forresisting the torque reaction of the stator 1 upon the drill'stem tube 2are shown typically by the fitted" screw 22 and the relative angularpositions ofsuccessive stators 1,] upon screwing togethertorque-producing sub-units is of no account so long as the dog couplings21 between successive units do not bottom" FIG. 3 illustrates the samecross-section as in FIG. 2, but with the rotor turned through an angleof 45 degrees relative to the stator.

It is essential in the practise of well drilling that the threadsbetween the lengths of drill pipe be always tightened. and as the normaldirection of operation can be taken as clockwise viewed from above thedirection of rotation of the hydraulic machine is such that its torquereaction tightens the connecting threads.

The outer drill pipe is rotated at slow speed by means of the well-known"Kelly above to avoid sticking in the borehole. and the tool is drivenfaster in the same direction by the means here described.

At the angular position shown in FIG. 3 in the cycle of operation of thehydraulic machine. torque is being produced by the abutments 5,5, thehydraulic pressure PIS reacting upon the vanes 9.10 crossing thechambers 3.3. the inlet ports 6,6 having just passed the now activevanes wilst the outgoing fluid at pressure P/O is continuously passingthru the outlet ports 7.7. At this instant in the cycle. and for a briefarcuate distance, dead" volumes of fluid D.D are trapped at constantvolume between the vanes 9.11 and 10,12. These volumes of fluid shortlymix with the outgoing fluid so that the passage of fluid thru themachine is continuous and uninterrupted. and the torque is constant.

FIG. 4 illustrates an upper thrust-bearing sub-unit primarily acting torelieve the rotor 4 (FIG. 1) of the torque-producing sub-unit below ofunbalanced endthrust due to the supply-pressure fluid P/S. Thethrustbearing rotor 23 is drilled axially providing passages 13,14,17 topass fluid at supply pressure P/S from the drill stem tubing eg. via acomponent known as a drill collar the weight of, which is not, however,imposed upon the thrust bearing of this sub-unit.

The positions in the rotor 23 opposite the outlet passages in thesub-unit below are left blind, so that whilst supply pressure PIS actson the upper end face of the rotor 23, outlet pressure P/O acts upon anequal area of its lower face.

Well-known selflaligning double thrust rolling bear ings 27 areemployed. essentially lubricated by an arrangement to minimize theleakage of grease or the ingress of the very hostile "mud" or slurryfluid. These means include a resilient plug 24 illustrated in the formof a blind-ended bellows mounted in the unit housing 37. The bearing ispre-charged with grease via the nip' ple 25, excluding air via the airvent plug 26, finally compressing the bellows which are also filled withgrease acted upon by the external pressure PM.

In service, the ambient pressure P/A acting without and within the pipestem and sub-units and contained within the earth may be say 4000 lbs.per sq. inch, but the grease will compress only according to itsvolumetric strain, with minimal tendency to leak.

The grease seals 32 of the sub units will, however, be subjected to thedifference of pressure P/S minus P/O actuating the torque-producingmachine, this pressure difference being of moderate magnitude, say 350lbs. per sq. inch.

While the threads connecting the various sub-units are standard in thewell-drilling industry, those of the various inserts and locking ringsmay be chosen of a self-locking pitch to diameter ratio. Close radialfits are not essential, as the dog-couplings must not bind.

FIG. 5 illustrates a rotating tool holder and thrust bearing sub-unit asfor a rotary well drilling or coring bit to be assembled below thetorque-producing sub unit or units (FIG. 1), furnished with a well knowntype of self-aligning rolling thrust bearing 29 selected for the heavyloads involved.

The lubricating and sealing arrangements illustrated are as for theupper thrust-bearing subunit (FIG. 4)

It is noted that the lowermost pipe thread is inverted, as inwell-drilling practise.

This sub-unit, shown shortened in FIG. 5, may be extended below thethrust bearing 29 to give adequate stability to the tool holder 30 in anelongated bearing 35, so incurring minimal misalignment to thedogcoupling 21 connecting it to the sub-unit above.

The central passage 17, coupled to the sub-unit above by a connectingsleeve 28 (FIG. 1). is terminated by a dumping valve 33, illustrated asa ball valve loaded by a varying rate coil spring 34 set for a somewhathigher lifting pressure than that required in the hydraulic fluid supplywhen the machine is exerting its maximum torque before stalling, thusgiving the drilling operator an indication of the condition, upon whichthe downward force is relieved by the draw-works.

All the fluid pumped down the well continues to discharge through thetool, and continues to force spoil up the borehole clearance E/C aroundthe drill-stem when stalling occurs.

The two passages thru the sub-unit above (FIG. 1) containing fluid atthe supply pressure P/S are coupled to the bottom thrust bearing rotarytool-holder 30 by means of connecting sleeves 28,28, but these fit intoblind bores in the rotor 30 in order to seal off said passages usingcommon components. The open passages 15,16 thru the rotor 30 conveyoutlet fluid to the tool.

Double thrust bearing provision 29 allows for the forcible withdrawal ofa stuck tool.

In the unlikely event of a complete seizure of the hydraulic sub-unit orunits, drilling can be continued without withdrawal by speeding up theKelly."

The sequence of assembly of the lower part of a well drain-stem frontthe top is as follows: To the series of drill pipes may be attached adrill collar ofgreat weight in order to feed the tool and to ensuretension at all times in the drill stem; any bent sub unit which may beemployed for directional drilling; a bypass" valve of well knownpattern. if used. discharging radially into the borehole clearance andset a somewhat higher lifting pressure than that ofthe valve 33illustrated in H6. 5 in order to give the drilling operator anindication of a stalled condition completely blocking the flow of fluidfrom issuring around the tool; the upper thrustbearing sub-unitdescribed (FlG.4); one or more torqueproducing sub-units described (FIGlthe rotating tool holder in the lower thrust-bearing sub-unit described(FlGS). and the tool.

The term "tool" is here used in its widest sense and includes a rotaryearth-boring or coring bit. or other form of cutting. scouring. orpenetrating device which may rotate. reciprocate. expand and contract.or urge axially with rotary actuation of its mechanism Having thus fullydescribed my invention. 1 claim as new and desire to secure by LettersPatent:

1. A hydraulic rotary well drilling machine comprising:

a. a first thrust bearing unit adapted to be secured to the lower end ofa drill stem.

b. a set of units comprising one or more torque producing units andadapted to be secured seriatim to the lower end of said first thrustbearing unit.

c. a second thrust bearing unit adapted to be secured to the lower endof said set of units.

d. each of said units (a). (b) and (c) comprising an outer member and aninner member relatively rotatable therein. said outer members comprisingmating coupling elements at their ends for assembling them together andsaid inner members comprising mating dog couplings at their ends forcoupling said inner members to rotate together.

c. said torque producing units of said set each having at least onehydraulic motor chamber therein between said outer and inner memberswith inlet and outlet ports thereto,

f. the inner members of said set of units having pressure fluid inletpassages extending longitudinally therethrough for mutual alignment whensaid units are assembled. and also having separate fluid outlet passagesextending longitudinally therethrough for mutual alignment when saidunits are assembled. said inlet and outlet ports being formed in saidinner members and communicating, respectively. with said inlet andoutlet passages therein. and said inlet passages being sleeve coupledbetween units of said set.

g. said first thrust bearing unit having a pressure fluid supply passagetherethrough connecting to said inlet passage when said units areassembled. and also sealing off said outlet passage when said units areassembled.

h. said second thrust bearing unit comprising mounting means forattachment of a well drilling tool thereto and sealing off said inletpassage when said units are assembled and having a relief-valved passagetherethrough coupled to said third passage.

2. A machine as claimed in claim 1, the units of said set and saidsecond thrust bearing having a third pressure fluid passage extendinglongitudinally therethrough and communicating with said supply passageand sleeve-coupled between units when said units are assembled. and saidsecond thrust bearing unit having a pressure relief valve thereincommunicating with said third passage.

3. A hydraulic rotary \vell drilling machine compris ing. incombination. a set of units including at least one torque producingunit. said torque producing unit ineluding:

a. a first member having a cylindrical bore with an annular groovetherein.

b. a second member rotatably fitting in said cylindrical bore and havingspacedprojections fitting in said annular groove and with said secondmember defining fluid chambers in said groove.

c. each said chamber being sub-divided by at least two longitudinallyslidable vanes per projection. said vanes being carried in slideways inthe bore of said first member equally spaced in planes radial to saidgroove.

d. cam means on said second member coupled to said vanes forlongitudinally sliding said vanes in said slideways,

. said vanes bearing thinner then said projections and each vane havinga fluid filled cut-out coinciding with and allowing passage therethroughof a projection when in one cam-controlled dwell position and crossingand subdividing the chamber when in another cam controlled dwellposition.

g. said second member having longitudinal fluid inlet and outletpassages therethrough open at both ends of said second member and havinginlet and outlet ports connecting said passages to said chambers.respectively, adjacent to opposite faces of said projections.

h. said second member having at its respective ends dog coupling unitsand sleeve means for sealing said inlet passage and having a third fluidpassage way extending therethrough not in communication with saidgroove.

. said ports being elongated arcuately to a sufficient extent to bridgesaid vanes for pressure equalization during sliding of said vanes,

j. said first member having threaded coupling elements at respective endadapted to mate with adja cent units of said set;

said drilling machine further comprising thrust hearing units withthreaded elements mating with said coupling elements for enablingassembly of said set between said thrust bearing units.

said thrust bearing units comprising means for closing said inletpassage at the lower end of said set and for closing said outlet passageat the upper end of said set.

4. A positive-displacement hydraulic rotary torqueproducing machineadapted to the practice of well drilling and cognate purposes forrotating tools. comprising a unit comprising a first rotor member ofcylindrical form closely fitting within a second cylindrical statormember arranged for relative rotation. the rotor carry ing abutmentsprojecting from its cylindrical surface in sets equally spaced arcuatelyand said sets spaced axially to rotate within and to partially occupyand to subdivide annular grooves formed within the stator andcorrespondingly spaced axially. said rotor including arcuately elongatedports for the admission and outlet of hydraulic fluid to and from thesub-division of said annular grooves in the stator, located adjacent tothe faces of said abutments. and the stator including groin es arrangedlongitudinally within its bore in planes inciuding the axis somewhatdeeper than said annular groin es therein. forming slideways tor vanes.vanes slidahly mounted in said slideways. said \anes touching the rotorand being essentially thinner than the abutmcnts and essentially two innumber for each abutment in one annular groo\e. each of said \aneshaving gateways therein correspondingly spaced to co incide with and toallow passage of said abutments simultaneously during rotation when inone axial position and said vanes crossing and subdividing said portionsof annular grooves when in another axially displaced position with theirgateways. full of fluid. clear of said annular grooves. there being atall times at least one vane crossing and dividing portions of annulargrooves between abutments simultaneously (a) to receive hydraulicpressure reaction to the forces rotating the abutments. and (b) at onearcuate portion of the rotation of the rotor to trap dead volumesoffluid between adjacent vanes at constant volume shortly releasing itto mix with outgoing fluid in its uninterrupted passage through themachine, generating constant torque, such axial motion of the vanesbeing controlled by a cam groove in the rotor having sinusoidal axialramps and having dwell arcuate portions engaging camfollowers projectingfrom said vanes so that the vanes are moved back and forth between theirdwell positions essentially whilst the ports are crossing them in orderto equalize the hydraulic pressures acting on opposite faces of thevanes to reduce the work of moving them, said gateways having clearancesfull of fluid at each side of the abutments to reduce the requirementsfor precision in said cam mechanism, and at the "lintels of saidgateways, said rotor including passages passing thru it in an axialdirection admitting and allowing exit of fluid by interconnectingrespective inlet and outlet ports leading fluid to and from thesubdivided portions of said annular grooves in the stator simultaneouslyand also an axial passageway conveying fluid not in communication withsaid grooves dog couplings at each end of said hydraulic machine rotorto mate with rotors of units attached above and below said machine saidcouplings being furnished with sleeves to connect and isolate thepassages thru successive coupled units which convey inlet fluid thepassages conveying outlet fluid essentially not being connected by suchsleeves in order to equalize end thrusts upon said rotor and to allowleakage fluid from each end of said rotor to mix with outgoing fluidsuch torque-producing hydraulic machine essentially being capable ofcombination with a thrust-bearing unit above and a thrust-bearing unitbelow said hydraulic machine. the latter forming a rotating tool holder5. A positive displacement hydraulic rotary torqueproducing machineaccording to claim 1 having a plurality of said units coupled togetherand to a first thrustbearing rotor contained in an attachable housinghaving axial passages thru it corresponding to the supply fluid passagesin the hydraulic machine rotor and connected thereto by isolatingsleeves but being blind opposite the outlet fluid passages in saidhydraulic machine rotor in order to relieve it of excess end thrust dueto supply pressure fluid.

6. A positive-displacement hydraulic rotary torque producing machine inaccordance with claim 5, said plurality of coupled units being coupledto a second thrust bearing rotor at the opposite end of the assemblyforming a rotating tool holder, and having its housing similarlyattachable and its rotor furnished with openended passageways thru it toconvey outlet fluid to too] and with an axial passageway to correspondto the central thru passage in the hydraulic machine rotor and connectedthereto by an isolating sleeve, said axial passage closed by aspring-loaded dump" valve set to lift at a pressure limiting thatapplicable to actuate the hydraulic machine blind bores being furnishedin the rotor to receive isolating sleeves sealing off the passageways inthe hydraulic machine rotor containing supply-pressure fluid.

7. A positive-displacement hydraulic rotary torqueproducing machineaccording to claim 6, said thrust bearing units being furnished withlubricant-retaining devices including resilient blind-ended bellows ordiaphragms so that when the assembly of associated units is inconditions of great hydraulic pressure without and within, as in welldrilling, the lubricating fluid can be compressed only to the extent ofits volumetric strain with minimal leakage or ingress of hydraulic fluidto the bearings

1. A hydraulic rotary well drilling machine comprising: a. a firstthrust bearing unit adapted to be secured to the lower end of a drillstem, b. a set of units comprising one or more torque producing unitsand adapted to be secured seriatim to the lower end of said first thrustbearing unit, c. a second thrust bearing unit adapted to be secured tothe lower end of said set of units, d. each of said units (a), (b) and(c) comprising an outer member and an inner member relatively rotatabletherein, said outer members comprising mating coupling elements at theirends for assembling them together and said inner members comprisingmating dog couplings at their ends for coupling said inner members torotate together, e. said torque producing units of said set each havingat least one hydraulic motor chamber therein between said outer andinner members with inlet and outlet ports thereto, f. the inner membersof said set of units having pressure fluid inlet passages extendinglongitudinally therethrough for mutual alignment when said units areassembled, and also having separate fluid outlet passages extendinglongitudinally therethrough for mutual alignment when said units areassembled, said inlet and outlet ports being formed in said innermembers and communicating, respectively, with said inlet and outletpassages therein, and said inlet passages being sleeve coupled betweenunits of said set, g. said first thrust bearing unit having a pressurefluid supply passage therethrough connecting to said inlet passage whensaid units are assembled, and also sealing off said outlet passage whensaid units are assembled, h. said second thrust bearing unit comprisingmounting means for attachment of a well drilling tool thereto andsealing off said inlet passage when said units are assembled and havinga relief-valved passage therethrough coupled to said third passage.
 2. Amachine as claimed in claim 1, the units of said set and said secondthrust bearing having a third pressure fluid passage extendinglongitudinally therethrough and communicating with said supply passageand sleeve-coupled between units when said units are assembled, and saidsecond thrust bearing unit having a pressure relief valve thereincommunicating with said third passage.
 3. A hydraulic rotary welldrilling machine comprising, in combination, a set of units including atleast one torque producing unit, said torque producing unit including:a. a first member having a cylindrical bore with an annular groovetherein, b. a second member rotatably fitting in said cylindrical boreand having spacedprojections fitting in said annular groove and withsaid second member defining fluid chambers in said groove, c. each saidchamber being sub-divided by at least two longitudinally slidable vanesper projection, said vanes being carried in slideways in the bore ofsaid first member equally spaced in planes radial to said groove, d. cammeans on said second member coupled to said vanes for longitudinallysliding said vanes in said slideways, f. said vanes bearing thinner thensaid projections and each vane having a fluid filled cut-out coincidingwith and allowing passage therethrough of a projection when in onecam-controlled dwell position and crossing and sub-dividing the chamberwhen in another cam controlled dwell position, g. said second memberhaving longitudinal fluid inlet and outlet passages therethrough open atboth ends of said second member and having inlet and outlet portsconnecting said passages to said chambers, respectively, adjacent toopposite faces of said projections, h. said second member having at itsrespective ends dog coupling units and sleeve means for sealing saidinlet passage and having a third fluid passageway extending therethroughnot in communication with said groove, i. said ports being elongatedarcuately to a sufficient extent to bridge said vanes for pressureequalization during sliding of said vanes, j. said first member havingthreaded coupling elements at respective end adapted to mate withadjacent units of said set; said drilling machine further comprisingthrust bearing units with threaded elements mating with said couplingelements for enabling assembly of said set between said thrust bearingunits, said thrust bearing units comprising means for closing said inletpassage at the lower end of said set and for closing said outlet passageat the upper end of said set.
 4. A positive-displacement hydraulicrotary torque-producing machine adapted to the practice of well drillingand cognate purposes for rotating tools, comprising a unit comprising afirst rotor member of cylindrical form closely fitting within a secondcylindrical stator member arranged for relative rotation, the rotorcarrying abutments projecting from its cylindrical surface in setsequally spaced arcuately and said sets spaced axially to rotate withinand to partially occupy and to subdivide annular grooves formed withinthe stator and correspondingly spaced axially, said rotor includingarcuately elongated ports for the admission and outlet of hydraulicfluid to and from the sub-division of said annular grooves in thestator, located adjacent to the faces of said abutments, and the statorincluding grooves arranged longitudinally within its bore in planesincluding the axis somewhat deeper than said annular grooves therein,forming slideways for vanes, vanes slidably mounted in said slideways,said vanes touching the rotor and being essentially thinner than theabutments and essentially two in number for each abutment in one annulargroove, each of said vanes having gateways therein correspondinglyspaced to coincide with and to allow passage of said abutmentssimultaneously during rotation when in one axial position and said vanescrossing and subdividing said portions of annular grooves when inanother axially displaced position with their gateways, full of fluid,clear of said annular grooves, there being at all times at least onevane crossing and dividing portions of annular grooves between abutmentssimultaneously (a) to receive hydraulic pressure reaction to the forcesrotating the abutments, and (b) at one arcuate portion of the rotationof the rotor to trap "dead" volumes of fluid between adjacent vanes atconstant volume shortly releasing it to mix with outgoing fluid in itsuninterrupted passage through the machine, generating constant torque,such axial motion of the vanes being controlled by a cam groove in therotor having sinusoidal axial ramps and having dwell arcuate portionsengaging cam-followers projecting from said vanes so that the vanes aremoved back and forth between their dwell positions essentially whilstthe ports are crossing them in order to equalize the hydraulic pressuresacting on opposite faces of the vanes to reduce the work of moving them,said gateways having clearances full of fluid at each side of theabutments to reduce the requirements for precision in said cammechanism, and at the "lintels" of said gateways, said rotor includingpassages passing thru it in an axial direction admitting and allowingexit of fluid by interconnecting respective inlet and outlet portsleading fluid to and from the subdivided portions of said annulargrooves in the stator simultaneously, and also an axial passagewayconveying fluid not in communication with said grooves, dog couplings ateach end of said hydraulic machine rotor to mate with rotors of unitsattached above and below said machine, said couplings being furnishedwith sleeves to connect and isolate the passages thru successive coupledunits which convey inlet fluid, the passages conveying outlet fluidessentially not being connected by such sleeves in order to equalize endthrusts upon said rotor and to allow leakage fluid from each end of saidrotor to mix with outgoing fluid, such torque-producing hydraulicmachine essentially being capable of combination with a thrust-bearingunit above and a thrust-bearing unit below said hydraulic machine, thelatter forming a rotating tool holder
 5. A positive displacementhydraulic rotary torque-producing machine according to claim 1 having aplurality of said units coupled together and to a first thrust-bearingrotor contained in an attachable housing having axial passages thru itcorresponding to the supply fluid passages in the hydraulic machinerotor and connected thereto by isolating sleeves but being blindopposite the outlet fluid passages in said hydraulic machine rotor inorder to relieve it of excess end thrust due to supply pressure fluid.6. A positive-displacement hydraulic rotary torque-producing machine inaccordance with claim 5, said plurality of coupled units being coupledto a second thrust bearing rotor at the opposite end of the assemblyforming a rotating tool holder, and having its housing similarlyattachable and its rotor furnished with openended passageways thru it toconvey outlet fluid to tool and with an axial passageway to correspondto the central thru passage in the hydraulic machine rotor and connectedthereto by an isolating sleeve, said axial passage closed by aspring-loaded "dump" valve set to lift at a pressure limiting thatapplicable to actuate the hydraulic machine, blind bores being furnishedin the rotor to receive isolating sleeves sealing off the passageways inthe hydraulic machine rotor containing supply-pressure fluid.
 7. Apositive-displacement hydraulic rotary torque-producing machineaccording to claim 6, said thrust bearing units being furnished withlubricant-retaining devices including resilient blind-ended bellows ordiaphragms so that when the assembly of associated units is inconditions of great hydraulic pressure without and within, as in welldrilling, the lubricating fluid can be compressed only to the extent ofits volumetric strain with minimal leakage or ingress of hydraulic fluidto the bearings.